Module overlay

A layer that sprites or text can manually be drawn in.

Overlay extends BoundObject

Properties

scene (read only) The Scene that contains Overlay
track_entity The Entity tracked by Overlay.
track_entity_edge The edge of the track_entity used to determine {0, 0}

Class Methods

Overlay:new () Create a new Overlay

Instance Methods

overlay:add_sprite (sprite) Add a Sprite to the Overlay.
overlay:draw_string (opts) Draw a string to Overlay.
overlay:draw_sprite (opts) Draw a Sprite to Overlay.

Configuration

font_name The file name of the TTF or OTF font to use when drawing strings.
font_size The font size in pixels to use when drawing strings.

Hooks

update (self) Called once each frame during the Scene's update cycle.
render (self) Called once each frame during the Scene's render cycle.


Properties

Properties. Significant fields on an instance.
scene
(read only) The Scene that contains Overlay
track_entity
The Entity tracked by Overlay.

This will make point {0, 0} track_entity_edge's point on the track_entity's bounding box.

track_entity_edge
The edge of the track_entity used to determine {0, 0} The edges are relative to the bounding box as follows:

 0---1---2
 |   |   |
 3---4---5
 |   |   |
 6---7---8

(0 is top left, 4 is center, 8 is bottom right)

Class Methods

Class Methods. Must be called on Class, with a capital leading character. e.g. Class:method("foo")
Overlay:new ()
Create a new Overlay

Returns:

    Overlay

Instance Methods

Instance Methods. Must be called on an instance of Class. e.g. instance:method("foo")
overlay:add_sprite (sprite)
Add a Sprite to the Overlay.

The main reason for this is so sprite can be updated. If you do not do this, SpriteAnimations will not advance.

Parameters:

  • sprite Sprite The sprite to add

Returns:

    nil
overlay:draw_string (opts)

Draw a string to Overlay.

This function is called with an "opts" parameter table. The parameters do not have to be in order.

Valid Options:

  • string = The string to draw. (required)

  • color = {r, g, b, a} vector representing the text color. Default {1, 1, 1, 1} (white).

  • origin = {x, y} baseline origin point relative to the screen center or entity edge in pixels. Default {0, 0}

  • align = The text alignment. Can be "left", "right" or "center". Default "left"

  • shadow_color = {r, g, b, a} vector representing the shadow color. Default nil.

  • shadow_offset = {x, y} vector representing the shadow offset in pixels. Default nil

Parameters:

  • opts table The named parameters.

Returns:

    nil

Usage:

     -- Red text with a white shadow, drawn in the center of the screen.
 overlay:draw_string({
     string = "Hello World!",
     align = "center",
     color = {1, 0, 0, 1},
     origin = {0, 0},
     shadow_color = {1, 1, 1, 1},
     shadow_offset = {0, 0}
 })
overlay:draw_sprite (opts)

Draw a Sprite to Overlay.

This function is called with an "opts" parameter table. The parameters do not have to be in order.

Valid Options:

  • sprite = The Sprite to draw. (required)

  • color = {r, g, b, a} vector representing the background color. Default {0, 0, 0, 0} (clear).

  • center = {x, y} point relative to the screen center or entity edge in pixels. Default {0, 0}

  • rotation = The angle of the sprite in degrees. Default 0

  • scale = Either a number or an {x, y} vector representing a scale factor. Default 1

Parameters:

  • opts table The named parameters.

Returns:

    nil

Usage:

     local mysprite = MySprite:new()
 overlay:draw_sprite({
     sprite = mysprite,
     center = {0, -100},
     rotation = 180,
     scale = {2, 1}
 })

Configuration

Configuration. Required by subclass declarations. Used when instantiating concrete subclasses.
font_name
The file name of the TTF or OTF font to use when drawing strings.

Defaults to nil

font_size
The font size in pixels to use when drawing strings.

Defaults to 0

Hooks

Hooks. Callbacks implemented in subclasses to customize behavior. Hooks are called on individual instances.
update (self)
Called once each frame during the Scene's update cycle. Modify values to display in this hook.

Parameters:

  • self Overlay The Overlay instance
render (self)
Called once each frame during the Scene's render cycle. Perform draw calls in this hook.

Parameters:

  • self Overlay The Overlay instance
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